The present invention relates generally to apparatus for laterally stressing, or stretching, a web of material carried in a selected direction along a conveyor path. More specifically, it relates to a stationary bowed spreader bar over which the web of material is carried.
In the manufacturing of paper and other flexible sheet materials, a web of such material may be carried in a selected direction along a conveyor path and is guided along such path by rollers. The material may be carried on a conveyor belt which may be made of metal wire, woven plastic, or other web carrying materials.
As the conveyor and web are carried through the process it may be necessary or desirable to provide a lateral stressing, or stretching, of the material either to remove wrinkles or other deviations, or to align the materials within the conveyor.
In the past various spreader rolls, or bowed rolls, have been used. These prior rolls have an outwardly bowed, or curved shape, and rotate about a fixed axle. Various operational problems occur with such devices, such as lubrication and flexural failures.
A general object of the present invention is to provide apparatus including a substantially stationary bowed spreader over which a web of material may be carried along a selected direction in a conveyor path, with the apparatus laterally stressing, or stretching, the web and overcoming many of the problems that have occurred in prior roller devices.
Another object of the present invention is to provide spreader apparatus which includes an elongate stationary spreader bar supported adjacent and extending substantially laterally of the conveyor path, the bar having a web support face which is convexly curved both about the longitudinal axis of the bar and along the longitudinal axis of the bar such that a web of a material carried thereover under tension is urged to spread, or stretch, laterally.
A further object of the invention is to provide such apparatus in which the spreader bar comprises a formed elongate support body having a degree of flexibility allowing the body to be bent into a bowed curve along its longitudinal axis and a plurality of hardened elements individually secured to and covering the face surface of the support body to form a web carrying face for the spreader bar.
A still further object of the invention is to provide such apparatus with a profiling support interposed between the base and support body to bend the support body into a desired bowed configuration. More specifically, the profiling support has a side which engages the carrier bar and is configured to bend the bar into a desired bowed configuration. Interchangeable profiling supports may be used to provide different bowed configurations for the bar.
Yet another object is to provide such apparatus in which the hardened elements are disposed in multiple rows and columns extending across the face surface of the support body with the hardened elements being secured at their rear faces to the support body and with front faces thereof forming the web carrying surface. Edge margins of an element are contiguous but unjoined to edge margins of adjacent elements, to permit bending of the carrier bar to varying bowed configurations.